Continual water hammer when running hot water

[Adam Preble]

I'm trying to get more information about what I might be seeing here. I have a home warranty that will probably get it repaired, but I wanted to make sure they sent the right guy out (plumber or water heater repairman).

When I'm running hot water in the kitchen, I'm getting a Continual pounding sound from the water heater. I think it's like water hammer, but it's at a rate like a woodpecker attacking a tree in a cartoon.

It's happened when running the sink on hot or the dishwasher. Any ideas?

[Shopdog]

A plumber can fix your problem.

Searcher

[Speedy Jim]

If it's a gas-fired heater and the hammer only occurs when the flame is on, then it is caused by heavy sediment buildup in the bottom of the tank. The water boils at the bottom and small bubbles "explode" into steam.

You will probably get the "Oh, that's normal..." and, in a sense it is.

There might be other causes for the noise, but that's one.

Jim

[Adam Preble]

I'd assume that would only happen when the heater itself was running. I get this problem after running the hot water for about 30 seconds. Would that loss of water engage the heater again?

[Speedy Jim]

Yes, only when the heater is firing. Monitor it and see if the burner is on when hammering.

Jim

[Walter R.]

Might be your faucet. Sometimes they set up a loud vibration. May happen only after the hot water hits the faucet. If it is a washer type faucet, take it apart.

Water hammer only occurs when you shut off the water too abruptly.

[Michael Daly]

Quite possibly you have a stretch of hot water pipe that is not supported properly. It starts to vibrate and makes a racket. If you can see the pipe, it will be very obvious. All you have to do is get a pipe support thingy (I'm drawing a blank on the proper name - age thing...) and attach the pipe to studs/joists in several places.

If the pipe in inside a wall/ceiling, you might have to rip open the drywall to fix.

Mike

[buffalobill]

troubleshooting the tank at:

see other discussions at:

[jimmiedee]

I had this problem an it turned out to be the cutoff valve on the water heater. WH was installed in both input and output valves. Dont remember which it was. It would hammer anytime I turned on the hot water at any location. Sometimes it would stop when I turned on the cold. A guy where where I bought the replacement valves asked me if I noticed which way they were installed before I took them out(I didnt) said they may be in backwards.